The most attractive free agent on the market agreed to a four-year deal with the Cleveland Indians worth $48 million. While that figure is substantially less than the Scott Boras client expected to get when the offseason began, it includes a vesting option that would tack on a fifth year worth another $12 million if Bourn reaches 550 plate appearances in 2016. Bourn will be 33 by then, a tricky age for ballplayers, but should be able to reach the benchmark as long as he’s (a) relatively healthy and (b) still batting leadoff for the Tribe.

Bourn joins Nick Swisher, who signed his own four-year deal, in Cleveland’s made-over outfield. Whereas Swish adds power and patience to fortify the heart of Terry Francona‘s lineup, Bourn brings speed and defense. A two-time Gold Glove winner and elite center fielder, Bourn has twice saved more runs with his glove than any other defender in baseball. He also uses his legs to his advantage on the basepaths, averaging 51 thefts per year since 2008 and leading the majors in steals over the past half-decade.

Though Bourn is nothing special with the bat (.704 career OPS), his combination of speed and defense at a premium position make him very valuable. According to Baseball-Reference, the two-time All-Star has been worth exactly 19 wins above replacement over the past four years. FanGraphs agrees and is even more generous, crediting him with 20.1 wins in that span, more than Josh Hamilton, Matt Kemp and Prince Fielder.

Rather than bring Bourn back, the Atlanta Braves opted to make a splash by shelling out $75 million for B.J. Upton instead. Considering that Bourn rates as the more valuable player and Cleveland nabbed him for two-thirds the cost, I’d say the Indians scored a solid bargain here. Since the going rate for a win on the open market is roughly $5 million these days, all Bourn has to do is contribute 10 wins over the next four seasons, an average of 2.5 per year, for the Indians to break even. Given that he was worth six wins last year alone, I’d bank on him living up to his end of the deal.

There is an element of risk with Bourn, though; the fear being that he could break down and become the next Carl Crawford. Like Crawford, most of Bourn’s value is tied up in his speed, a skill that diminishes with age (though Juan Pierre and Ichiro Suzuki are still going strong). Now that he’s on the wrong side of 30, Bourn has already peaked, and it’s possible he’s about to enter his decline phase. I think Bourn still has a few four-to-five win seasons left in the tank, but wouldn’t be surprised to see him struggle a bit in his first year with the Tribe as he adjusts to the new league, cit, and ballpark, as most free agents seem to do after signing a new contract.

But even if he slumps, at least Bourn figures to play everyday, which is more than Grady Sizemore can say.